Typically, a combustor system for a gas turbine engine includes outer and inner casings that house outer and inner liners. The liners and casings are radially spaced apart to form a passage for compressed air. The inner and outer liners form a combustion chamber within which compressed air mixes with fuel and is ignited. As such, each of the liners includes a hot side exposed to hot combustion gases and a cold side facing the passage formed between the liners and the casings. The liner may also be a dual wall construction, where the side of the liner which is exposed to the combustion gases is thermally decoupled from the side which is exposed to compressor discharge gases, thereby forming an intervening cavity.
In typical combustors, a plurality of effusion cooling holes supply a thin layer of cooling air that insulates the hot sides of the liners from extreme combustion temperatures. The liners also include major openings, much larger than the cooling holes, for the introduction of compressed air to feed the combustion process. The thin layer of cooling air can be disrupted by flow through the major openings, potentially resulting in elevated liner temperatures adjacent the major openings. Elevated or uneven temperature distributions within the liners can promote undesired oxidation of the liner material, coating-failure, or thermally induced stresses that degrade the effectiveness, integrity, and life of the liners.
It is known to arrange cooling holes in a dense grouping upstream of major openings, in the primary combustion zone where higher radiation loads and temperatures are located, to distribute ample cooling airflow in regions via film cooling and effective heat removal through the thickness of the liners by convection along the surfaces of the holes. Disadvantageously, the greater flow through the major openings can disrupt the flow of cooling air around the major openings. This situation can result in a deficiency of cooling air downstream of the major openings that may cause an undesirable increase in liner temperature. Further, the overall amount of cooling airflow is limited and it is therefore desirable to efficiently allocate available cooling airflow to provide even temperature distribution throughout the liner.
Accordingly, it is desirable to develop combustor systems with liners that improve cooling layer properties, particularly adjacent to major openings, to eliminate uneven temperature distributions or undesirable temperature levels. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description of the invention and the appended claims, taken in conjunction with the accompanying drawings and this background of the invention.